There have been known that various drugs are accumulated in biological samples including human body such as hair, nail, body hair, skin, bone and the like. Drugs accumulated in biological samples have conventionally been analyzed by a wet process. Namely, biological samples are finely cut, optionally washed, dissolved by alkaline treatment and extracted with a solvent for extracting drugs. The extracted liquid is then subjected to gas chromatography or liquid chromatography, if necessary to mass spectrometry to identify a target drug. The method generally takes at least one to two days and requires considerable labor and expensive apparatus (non-patent documents 1 to 3).    Non-patent document 1 Journal of Medical Technology, Vol. 39, No. 4 (1995), p. 439-446    Non-patent document 2 Pharmacia, Vol. 34, No. 9 (1998), p. 889-894    Non-patent document 3 Biomedical Chromatography 18:655-661 (2004)